This invention relates to a developing method for visualizing an electrostatic latent image formed on a latent image support and in particular to a developing method and a developing device effective for forming an image requiring high image quality and an image formation system using the developing device.
In recent years, digital image output machines have increased remarkably with the widespread use of facsimiles and personal computers.
For example, demands for digital image output also grow for electrophotographic image formation systems and digitization with a digital-compatible exposure device installed in a conventional analog system moves.
In such an environment, the user who prepares documents becomes more flexible in planning to make his or her intention known to readers impressively documents with various fonts, hollow characters, shaded areas, halftone crosshatched background, etc., are zooming.
Although the conventional electrophotographic image formation systems have met user's demands centering on line drawings mainly composed of simple characters, some electrophotographic image formation systems unfortunately produce image defects on some of image patterns as in the example described above.
The image defects on which the inventor et al. focus attention are those occurring when backgrounds are halftone crosshatched. More particularly, when the background of a plane image having the maximum toner amount per unit area, such as a heavy line image or a solid plane image, which will be hereinafter referred to as "solid image," is crosshatched uniformly, a crosshatch skip (a skip in the halftone area adjoining the solid area) occurs on the boundary between the solid image and the background.
According to the study of the inventor et al., the skip in the halftone area adjoining the solid area is a technical problem that can occur regardless of which of dual and mono component developing systems is used as a developing device of an electrophotographic image formation system.